Emitter, and tube for drip irrigation

ABSTRACT

This emitter is constituted from an emitter body, a film, and a cover. The emitter has a water intake part, a discharge part, a first flow path, a second flow path, a flow reduction part, a flow path opening/closing part, a pressure-reducing flow path, and a bypass flow path. When the pressure of an irrigation liquid flowing through a tube is less than a first pressure, the irrigation liquid passes through the pressure-reducing flow path and the bypass flow path and is guided to the discharge part. When the pressure of the irrigation liquid flowing through the tube is equal to or greater than the first pressure, the second flow path is closed by the flow path opening/closing part, and the irrigation liquid taken in from the water intake part passes through the pressure-reducing flow path and is guided to the discharge part.

TECHNICAL FIELD

The present invention relates to an emitter, and a drip irrigation tubeincluding the emitter.

BACKGROUND ART

Conventionally, a drip irrigation method is known as a method forculturing plants. In the drip irrigation method, a drip irrigation tubeis disposed on the soil where plants are planted, and irrigation liquidsuch as water and liquid fertilizer is dropped to the soil from the dripirrigation tube. The drip irrigation method has been increasinglyattracting attention in recent years since the method can minimize theconsumption rate of the irrigation liquid.

Normally, the drip irrigation tube includes a tube provided with aplurality of through holes for discharging irrigation liquid, and aplurality of emitters (also called “drippers”) for dischargingirrigation liquid from respective through holes. In addition, emitterswhich are joined on the inner wall surface of a tube (see, for example,PTL 1), and emitters which are inserted to a tube from the outside ofthe tube are known.

PTL 1 discloses an emitter configured to be joined on the inner wallsurface of a tube. The emitter disclosed in PTL 1 includes a firstmember including a water intake port for receiving irrigation liquid, asecond member including an outlet for discharging the irrigation liquid,and a film member disposed between the first member and the secondmember. On the inside of the first member, a valve seat part disposed isformed in such a manner as to surround the water intake port, and apressure reducing groove that serves as a part of a pressure reducingchannel is opened. In the film member, a through hole is formed at aposition corresponding to the downstream end of the pressure reducinggroove.

When the first member, the film member and the second member arestacked, the pressure reducing channel is formed, and the film membermakes contact with the valve seat part to close the water intake port.In addition, a channel for carrying the irrigation liquid from the waterintake port to the outlet is formed.

In the emitter disclosed in PTL 1, when the pressure of the irrigationliquid in the tube is equal to or greater than a predetermined pressure,the film member closing the water intake port is pushed by theirrigation liquid, and the irrigation liquid flows into the emitter. Thepressure of the irrigation liquid having entered the emitter is reducedby the reducing channel, and thus the irrigation liquid isquantitatively discharged from the outlet.

CITATION LIST Patent Literature PTL 1 Japanese Patent ApplicationLaid-Open No. 2010-046094 SUMMARY OF INVENTION Technical Problem

In the drip irrigation tube using the emitter disclosed in PTL 1,however, the irrigation liquid flows into the emitter only when thepressure of the irrigation liquid in the tube is equal to or greaterthan the predetermined pressure, and as such the tube disclosed in PTL 1does not function when the pressure of the irrigation liquid in the tubeis significantly low. Consequently, emitters disposed at a positionremote from the liquid feed pump for sending the irrigation liquid tothe tube do not appropriately function while emitters near the liquidfeed pump appropriately function. Consequently, the flow rate of theirrigation liquid to be supplied varies depending on the wateringposition, and the watering distance is limited.

In view of this, an object of the present invention is to provide anemitter and a drip irrigation tube capable of quantitatively dischargingirrigation liquid not only when the pressure of the irrigation liquid ishigh, but also when the pressure is low.

Solution to Problem

To solve the above-mentioned problems, an emitter according to anembodiment of the present invention includes an emitter main body, afilm having flexibility disposed on a first surface of the emitter mainbody, and a cover for positioning the film with respect to the emittermain body, the emitter being configured to be joined on an inner wallsurface of a tube configured to distribute irrigation liquid at aposition corresponding to a discharging port communicating betweeninside and outside of the tube, the emitter being configured toquantitatively discharge the irrigation liquid in the tube to theoutside of the tube from the discharging port, the emitter including: aliquid intake part for receiving the irrigation liquid; a dischargingpart disposed in a second surface of the emitter main body andconfigured to discharge the irrigation liquid, the second surface beingopposite to the first surface and being configured to face thedischarging port; a first channel configured to connect the liquidintake part and the discharging part together, and to distribute theirrigation liquid; a second channel configured to connect the liquidintake part and the discharging part together, and to distribute theirrigation liquid; a flow rate reducing part disposed in the firstchannel and including a flow rate reducing recess opening at the firstsurface and the film closing an opening of the flow rate reducingrecess, the flow rate reducing part being configured to reduce a flowrate of the irrigation liquid flowing to the discharging port bydeformation of the film in accordance with a pressure of the irrigationliquid in the tube; a channel opening-closing part disposed in thesecond channel and including a channel opening-closing recess opening atthe first surface and the film closing an opening of the channelopening-closing recess, the channel opening-closing part beingconfigured to open and close the second channel by deformation of thefilm in accordance with a pressure of the irrigation liquid in the tube;a pressure reducing channel disposed in the first channel locatedupstream of the flow rate reducing part, the pressure reducing channelbeing configured to guide, to the flow rate reducing part, theirrigation liquid received from the liquid intake part while reducing apressure of the irrigation liquid received from the liquid intake part;and a bypass channel disposed in the second channel located upstream ofthe channel opening-closing part, the bypass channel being configured toguide, to the channel opening-closing part, the irrigation liquidreceived from the liquid intake part while maintaining a pressure of theirrigation liquid received from the liquid intake part at a pressurehigher than a pressure of the irrigation liquid which has flown throughthe pressure reducing channel. When the pressure of the irrigationliquid flowing through the tube is lower than a first pressure, theirrigation liquid received from the liquid intake part is guided to thedischarging part through the pressure reducing channel and the bypasschannel. When the pressure of the irrigation liquid flowing through thetube is equal to or higher than the first pressure, the second channelis closed by the channel opening-closing part, and the irrigation liquidreceived from the liquid intake part is guided to the discharging partthrough the pressure reducing channel.

In addition, to solve the above-mentioned problems, a drip irrigationtube according to an embodiment of the present invention includes: atube including a discharging port for discharging irrigation liquid; andthe above-mentioned emitter, the emitter being joined on the inner wallsurface of the tube at a position corresponding to the discharging port.

Advantageous Effects of Invention

With the emitter and the drip irrigation tube according to theembodiment of the present invention, it is possible to quantitativelydischarge irrigation liquid not only when the pressure of the irrigationliquid is high, but also when the pressure is low. In addition, theemitter and the drip irrigation tube according to the embodiment of thepresent invention can achieve quantitative watering over long distance.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a drip irrigation tube;

FIGS. 2A and 2B are perspective views of an emitter;

FIGS. 3A to 3D illustrate a configuration of the emitter;

FIGS. 4A to 4C are sectional views of the emitter;

FIGS. 5A to 5D illustrate a configuration of an emitter main body;

FIGS. 6A to 6C illustrate a configuration of a film;

FIGS. 7A to 7D illustrate a configuration of a cover;

FIGS. 8A to 8C are sectional views for describing operations of theemitter; and

FIG. 9 is a graph showing an exemplary relationship between a pressureof irrigation liquid in the drip irrigation tube and a flow rate ofirrigation liquid dropped from a discharging port.

DESCRIPTION OF EMBODIMENTS

An embodiment of the present invention is elaborated below withreference to the accompanying drawings.

Configurations of Drip Irrigation Tube and Emitter

FIG. 1 is a sectional view along the axial direction of drip irrigationtube 100 according to an embodiment of the present invention.

As illustrated in FIG. 1, drip irrigation tube 100 includes tube 110 andemitter 120.

Tube 110 is a pipe for carrying irrigation liquid. The material of tube110 is not limited. In the present embodiment, the material of tube 110is polyethylene. In the wall of tube 110, a plurality of dischargingports 111 for discharging irrigation liquid are formed at apredetermined interval (for example, 200 to 500 mm) in the axialdirection of tube 110. The diameter of the opening of discharging port111 is not limited as long as irrigation liquid can be discharged. Inthe present embodiment, the diameter of the opening of discharging port111 is 1.5 mm. Emitters 120 are joined on the inner wall surface of tube110 at respective positions corresponding to discharging ports 111. Thecross-sectional shape and the cross-sectional area of tube 110 in thedirection perpendicular to the axial direction of tube 110 are notlimited as long as emitter 120 can be disposed inside tube 110.

Drip irrigation tube 100 is assembled by joining the rear surface ofemitter 120 to the inner wall surface of tube 110. The method of joiningtube 110 and emitter 120 is not limited. Examples of the method ofjoining tube 110 and emitter 120 include welding of the resin materialof tube 110 or emitter 120, bonding with an adhesive agent and the like.Normally, discharging port 111 is formed after tube 110 and emitter 120are joined to each other. Discharging port 111 may be formed before tube110 and emitter 120 are joined to each other.

Emitter 120 is joined on the inner wall surface of tube 110 in such amanner as to cover discharging port 112. The shape of emitter 120 is notlimited as long as emitter 120 can make intimate contact with the innerwall surface of tube 110 and can cover discharging port 111. In thepresent embodiment, in the cross-section of emitter 120 in the directionperpendicular to the axial direction of tube 110, the rear surface,which is joined to the inner wall surface of tube 110, of emitter 120has a substantially arc shape protruding toward the inner wall surfaceof tube 110 along the inner wall surface of tube 110. In addition, inplan view, emitter 120 has a substantially rectangular shape withchamfered four corners. The size of emitter 120 is not limited. In thepresent embodiment, emitter 120 has a long side length of 25 mm, a shortside length of 8 mm, and a height of 2.5 mm.

FIGS. 2A to 4C illustrate a configuration of emitter 120. FIG. 2A is aperspective view of emitter 120 as viewed from the front surface (firstsurface) side, and FIG. 2B is a perspective view of emitter 120 asviewed from the rear surface (second surface) side. FIG. 3A is a planview of emitter 120, FIG. 3B is a bottom view of emitter 120, FIG. 3C isa front view of emitter 120, and FIG. 3D is a right side view of emitter120. FIG. 4A is a sectional view taken along line A-A of FIG. 3A, FIG.4B is a sectional view taken along line B-B of FIG. 3A, and FIG. 4C is asectional view taken along line C-C of FIG. 3A. FIGS. 5A to 5Dillustrate a configuration of emitter main body 121. FIG. 5A is a planview of emitter main body 121, FIG. 5B is a bottom view of emitter mainbody 121, FIG. 5C is a front view of emitter main body 121, and FIG. 5Dis a right side view of emitter main body 121. FIGS. 6A to 6C illustratea configuration of film 122. FIG. 6A is a plan view of film 122, FIG. 6Bis a front view of film 122, and FIG. 6C is a right side view of film122. FIGS. 7A to 7D illustrate a configuration of cover 123. FIG. 7A isa plan view of cover 123, FIG. 7B is a bottom view of cover 123, FIG. 7Cis a front view of cover 123, and FIG. 7D is a right side view of cover123.

As illustrated in FIGS. 2A to 4C, emitter 120 is composed of emittermain body 121, film 122, and cover 123. That is, emitter 120 accordingto the present embodiment has a 3-body structure. In addition, emitter120 includes liquid intake part 131, pressure reducing channel 141, flowrate reducing part 161, channel opening-closing part 171, bypass channel151, and discharging part 181.

A main portion of emitter 120 is formed in emitter main body 121. Asillustrated in FIGS. 4A to 5D, in the present embodiment, pressurereducing groove 142 that forms pressure reducing channel 141, flow ratereducing recess 162 that forms flow rate reducing part 161, bypassgroove 152 that forms bypass channel 151, channel opening-closing recess172 that forms channel opening-closing part 171, and discharging part181 are formed in emitter main body 121. Pressure reducing groove 142,flow rate reducing recess 162, bypass groove 152, and channelopening-closing recess 172 open at the first surface. In addition,discharging part 181 is disposed in the second surface.

Film 122 deforms in accordance with the pressure of the irrigationliquid in tube 110 to thereby adjust the amount of the irrigation liquidto be sent to discharging part 181. Film 122 is disposed on the frontsurface (first surface) side of emitter main body 121. The shape of film122 in plan view is not limited as long as the above-described functioncan be ensured. As illustrated in FIGS. 6A to 6C, in the presentembodiment, the shape of film 122 in plan view is identical to theexternal shape of the first surface of emitter main body 121. Inaddition, as illustrated in FIGS. 4A to 6C, in the present embodiment,film 122 includes first diaphragm part 166 that forms flow rate reducingpart 161 and second diaphragm part 176 that forms channelopening-closing part 171, and, second intake through hole 134 that formsliquid intake part 131 is formed therein. Film 122 has a thickness of0.3 mm, for example.

Cover 123 positions film 122 with respect to the first surface ofemitter main body 121. The shape of cover 123 is not limited as long asthe above-described function can be ensured. As illustrated in FIGS. 7Ato 7D, in the present embodiment, cover 123 has a shape of a box withone open side. In addition, cover 123 is formed such that emitter mainbody 121 having film 122 disposed on the first surface is fitted to theinside of cover 123. In addition, in the present embodiment, liquidintake screen part 132 that forms liquid intake part 131, first screenpart 167 that forms flow rate reducing part 161, and second screen part177 that forms channel opening-closing part 171 are formed in cover 123.

Emitter 120 is produced by disposing film 122 to the first surface sideof emitter main body 121, and then by fitting emitter main body 121 tocover 123 such that film 122 makes contact with the bottom surface ofcover 123.

The material of emitter main body 121 and cover 123 is not limited aslong as the material has an elasticity that allows fitting of emittermain body 121 to cover 123. Examples of the material of emitter mainbody 121 and cover 123 include resins such as polyethylene and silicone,and a rubber. In the present embodiment, polyethylene is used as thematerial of emitter main body 121 and cover 123 in view of manufacturingcost and required elasticity. In addition, the material of film 122 isnot limited as long as the material allows appropriate deformation inaccordance with the pressure of the irrigation liquid in tube 110.Examples of the material of film 122 include a resin such aspolyethylene and silicone, and a rubber. In the present embodiment,silicone is used as the material of film 122 in view of requiredelasticity. While film 122 is shaped with a material different from thatof emitter main body 121 and cover 123 in the present embodiment,emitter main body 121, cover 123, and film 122 may be shaped with thesame material. The flexibility of emitter main body 121, film 122 andcover 123 can be adjusted by use of elastic resin material. Examples ofthe method of adjusting the flexibility of emitter main body 121, film122 and cover 123 include selection of an elastic resin, adjustment ofthe mixing ratio of an elastic resin material to a hard resin material,and the like. Each of emitter main body 121, film 122 and cover 123 canbe manufactured by injection molding, for example. In addition, film 122may be produced by cutting out a commercially available film.

When film 122 is disposed on the first surface of emitter main body 121,pressure reducing groove 142 and bypass groove 152 serve as pressurereducing channel 141 and bypass channel 151, respectively. Meanwhile,flow rate reducing recess 162 and channel opening-closing recess 172serve as flow rate reducing part 161 and channel opening-closing part171, respectively. In addition, when cover 123 is attached to emittermain body 121 provided with film 122, liquid intake screen part 132,first intake through hole 133 and second intake through hole 134 serveas liquid intake part 131. In this manner, first channel 153, whichincluding liquid intake part 131, pressure reducing channel 141, flowrate reducing part 161 and discharging part 181, and connects liquidintake part 131 and discharging part 181 together, is formed. Inaddition, second channel 154, which includes liquid intake part 131,bypass channel 151, channel opening-closing part 171 and dischargingpart 181, and connects liquid intake part 131 and discharging part 181together, is formed. Each of first channel 153 and second channel 154distributes irrigation liquid from liquid intake part 131 to dischargingpart 181.

Liquid intake part 131 is disposed on the front surface side of emitter120 (see FIG. 4A). Liquid intake part 131 includes liquid intake screenpart 132, first intake through hole 133 (see FIG. 7A) and second intakethrough hole 134 (see FIG. 6A).

Liquid intake screen part 132 prevents entry, into emitter main body121, of floating matters in the irrigation liquid to be taken intoemitter 120. Liquid intake screen part 132 is formed in the entirety ofthe front surface of cover 123. Liquid intake screen part 132 opens tothe interior of tube 110, and includes cover recess 135 and a pluralityof projected lines 136.

Cover recess 135 is a single recess formed in the entirety of the topsurface of cover 123. The depth of cover recess 135 is not limited, andis appropriately set in accordance with the size of emitter 120.Projected lines 136 are disposed on the bottom surface of cover recess135. In addition, first intake through hole 133, flow rate reducingthrough hole 168 and channel opening-closing through hole 178 open atthe bottom surface of cover recess 135 (see FIG. 7A and FIG. 7B).

Projected lines 136 are disposed on the bottom surface of cover recess135. The installation and number of projected lines 136 are not limitedas long as entry of floating matters of irrigation liquid can beprevented while allowing entry of the irrigation liquid from the openingside of cover recess 135. In the present embodiment, projected line 136is disposed along the longitudinal axial direction of emitter 120.Projected line 136 may be formed such that the width of projected line136 decreases from the bottom surface of cover recess 135 toward thefront surface of cover 123, or that the width of projected line 136 isthe same from the bottom surface of cover recess 135 to the frontsurface of cover 123.

First intake through hole 133 opens at the bottom surface of coverrecess 135. The shape and number of first intake through hole 133 arenot limited as long as the irrigation liquid taken into cover recess 135can be guided into emitter main body 121 through second intake throughhole 134. In the present embodiment, first intake through hole 133 isfive rectangular holes formed along the longitudinal axial direction ofthe bottom surface of cover recess 135 (see FIG. 7B).

Second intake through hole 134 is formed in film 122. The shape andnumber of second intake through hole 134 are not limited as long as theirrigation liquid taken from first intake through hole 133 can be guidedto pressure reducing channel 141 and bypass channel 151. In the presentembodiment, second intake through hole 134 has a shape of two circles(see FIG. 6A).

Liquid intake screen part 132 prevents the floating matters of theirrigation liquid which has passed through tube 110 from entering coverrecess 135, and this irrigation liquid is then taken into emitter mainbody 121 through first intake through hole 133 and second intake throughhole 134.

Pressure reducing channel 141 (pressure reducing groove 142), which isdisposed in first channel 153 located upstream of flow rate reducingpart 161, connects liquid intake part 131 and flow rate reducing part161 together. Pressure reducing channel 141 (pressure reducing groove142) guides the irrigation liquid taken from liquid intake part 131 toflow rate reducing part 161 while reducing the pressure of theirrigation liquid. Pressure reducing channel 141 is disposed at a centerportion of emitter 120. Pressure reducing channel 141 is composed ofpressure reducing groove 142, and film 122 for closing the opening ofpressure reducing groove 142. Pressure reducing groove 142 is formed inthe front surface (first surface) of emitter main body 121. The shape ofpressure reducing groove 142 is not limited as long as theabove-described function can be ensured as pressure reducing channel141. In the present embodiment, pressure reducing groove 142 has azigzag shape in plan view. In pressure reducing groove 142, protrusions143, each of which has a substantially triangular prism shape andprotrudes from the inner surface of pressure reducing groove 142, arealternately disposed along the flow direction of the irrigation liquid.In plan view, protrusions 143 are disposed such that the tip of eachprotrusion 143 does not cross the central axis of end pressure reducinggroove 142. When film 122 is disposed on the first surface of emittermain body 121, pressure reducing groove 142 and a part of the rearsurface of film 122 form pressure reducing channel 141. At least a partof the irrigation liquid taken from liquid intake part 131 is guided toflow rate reducing part 161 while the pressure thereof is reduced byreducing channel 141. As elaborated later, pressure reducing channel 141operates mainly when the pressure of irrigation liquid is high.

Bypass channel 151 (bypass groove 152), which is disposed in secondchannel 154 located upstream of channel opening-closing part 171,connects liquid intake part 131 and channel opening-closing part 171together. Bypass channel 151 (bypass groove 152) guides, to channelopening-closing part 171, the irrigation liquid taken from liquid intakepart 131 while maintaining the pressure of the liquid at a value higherthan that of the irrigation liquid which has flown through pressurereducing channel 141 (pressure reducing groove 142). When film 122 isdisposed on the first surface of emitter main body 121, bypass groove152 and a part of the rear surface of film 122 form bypass channel 151.A part of the irrigation liquid taken from liquid intake part 131 passesthrough bypass channel 151 and is guided to channel opening-closing part171. As elaborated later, bypass channel 151 operates only when thepressure of the irrigation liquid is low.

It is to be noted that a channel screen part may be disposed in bypassgroove 152. The channel screen part captures floating matters in theirrigation liquid which have not collected by liquid intake screen part132. The configuration of the channel screen part is not limited as longas the above-described function can be ensured. For example, the channelscreen part is a plurality of columnar protrusions disposed on thebottom surface of bypass groove 152.

Flow rate reducing part 161 is disposed between pressure reducingchannel 141 and discharging part 181 in first channel 153. Flow ratereducing part 161 sends the irrigation liquid to irrigation liquiddischarging part 181 while reducing the flow rate of the irrigationliquid in accordance with the pressure of the irrigation liquid in tube110. The configuration of flow rate reducing part 161 is not limited aslong as the above-described function can be ensured. In the presentembodiment, flow rate reducing part 161 includes flow rate reducingrecess 162, first valve seat part 163, communication groove 164, firstdischarging through hole 165 communicated with discharging part 181,first diaphragm part 166, which is a part of film 122, and first screenpart 167.

The shape of flow rate reducing recess 162 in plan view is not limited.The shape of flow rate reducing recess 162 in plan view may be asubstantially rectangular shape with chamfered four corners, or asubstantially semicircular shape. In the present embodiment, the shapeof flow rate reducing recess 162 in plan view is a substantiallyrectangular shape with chamfered four corners. First discharging throughhole 165 communicated with discharging part 181 opens at the bottomsurface of flow rate reducing recess 162, and first valve seat part 163is disposed in the bottom surface of flow rate reducing recess 162. Inaddition, pressure reducing channel 141 (pressure reducing groove 142)is connected with the side surface of flow rate reducing recess 162. Thedepth of flow rate reducing recess 162 is not limited as long as thedepth is equal to or greater than the depth of communication groove 164and pressure reducing groove 142.

First discharging through hole 165 opens at a center portion of thebottom surface of flow rate reducing recess 162, and is communicatedwith discharging part 181. First valve seat part 163 is disposed in thebottom surface of flow rate reducing recess 162 in such a manner as tosurround first discharging through hole 165. First valve seat part 163is formed such that first diaphragm part 166 can make intimate contactwith first valve seat part 163 when the pressure of the irrigationliquid flowing through tube 110 is the second pressure or greater. Whenfirst diaphragm part 166 makes contact with first valve seat part 163,the flow rate of the irrigation liquid flowing into discharging part 181from flow rate reducing recess 162 is reduced. The shape of first valveseat part 163 is not limited as long as the above-described function canbe ensured. In the present embodiment, first valve seat part 163 has ashape of an annular protrusion. Communication groove 164, whichcommunicates between the inside of flow rate reducing recess 162 andfirst discharging through hole 165, is formed in a part of the region offirst valve seat part 163 where first diaphragm part 166 can makeintimate contact with first valve seat part 163.

First diaphragm part 166 is a part of film 122. First diaphragm part 166is disposed as a partition between the inside of flow rate reducingrecess 162 and the inside of tube 110. First diaphragm part 166 deformsin such a manner as to make contact with first valve seat part 163 inaccordance with the pressure of the irrigation liquid in tube 110. To bemore specific, first diaphragm part 166 deforms toward first valve seatpart 163 as the pressure of the irrigation liquid increases, and finallymakes contact with first valve seat part 163. Even when first diaphragmpart 166 is in intimate contact with first valve seat part 163, neitherof the end portion of pressure reducing channel 141, first dischargingthrough hole 165, nor communication groove 164 is closed by firstdiaphragm part 166, and thus the irrigation liquid sent from pressurereducing channel 141 can be sent to discharging part 181 throughcommunication groove 164 and first discharging through hole 165.

First screen part 167 sends the irrigation liquid to the front surfaceof first diaphragm part 166 with almost no change in pressure of theirrigation liquid. First screen part 167 includes a part of cover recess135, some of projected lines 136, and flow rate reducing through hole168. Flow rate reducing through hole 168 is formed in a bottom portionof cover 123 at a position corresponding to first diaphragm part 166.The shape and number of flow rate reducing through hole 168 are notlimited as long as the above-described function can be ensured. Theshape of flow rate reducing through hole 168 in plan view may be acircular shape or a rectangular shape. In the present embodiment, flowrate reducing through hole 168 has a rectangular shape in plan view. Inaddition, the number of flow rate reducing through hole 168 is notlimited. In the present embodiment, flow rate reducing through holes 168is five long holes formed along the minor axis direction of the bottomsurface of cover recess 135. The long holes are covered with projectedlines 136, and therefore each flow rate reducing through hole 168appears to be divided into multiple through holes as viewed from thefront side.

Channel opening-closing part 171 is disposed between bypass channel 151and discharging part 181 in second channel 154. In accordance with thepressure in tube 110, channel opening-closing part 171 opens secondchannel 154 and sends the irrigation liquid to discharging part 181. Theconfiguration of channel opening-closing part 171 is not limited as longas the above-described function can be ensured. In the presentembodiment, channel opening-closing part 171 includes channelopening-closing recess 172, second valve seat part 173, seconddischarging through hole 175 communicated with discharging part 181,second diaphragm part 176, which is a part of film 122, and secondscreen part 177.

The shape of channel opening-closing recess 172 in plan view is notlimited. The shape of channel opening-closing recess 172 in plan viewmay be a substantially rectangular shape with chamfered four corners, ora substantially semicircular shape. In the present embodiment, channelopening-closing recess 172 has a substantially rectangular shape withchamfered four corners in plan view. Second discharging through hole 175communicated with discharging part 181, and second valve seat part 173are disposed in the bottom surface of channel opening-closing recess172. In addition, bypass channel 151 (bypass groove 152) is connectedwith the side surface of channel opening-closing recess 172. Secondvalve seat part 173 is disposed on the first surface side relative tofirst valve seat part 163. With this configuration, when film 122 isdeformed under the pressure of the irrigation liquid, film 122 makescontact with second valve seat part 173 before making contact with firstvalve seat part 163.

Second discharging through hole 175 opens at a center portion of thebottom surface of channel opening-closing recess 172, and iscommunicated with discharging part 181. Second valve seat part 173 isdisposed in the bottom surface of channel opening-closing recess 172 insuch a manner as to surround second discharging through hole 175. Inaddition, second valve seat part 173 is disposed to face seconddiaphragm part 176 without making contact with second diaphragm part176, and is formed such that second diaphragm part 176 can make intimatecontact with second valve seat part 173 when the pressure of theirrigation liquid flowing through tube 110 is the first pressure orgreater. When the pressure of the irrigation liquid flowing through tube110 is the first pressure or greater, second diaphragm part 176 makesintimate contact with second valve seat part 173 to close seconddischarging through hole 175, and thus closes second channel 154. Theshape of second valve seat part 173 is not limited as long as theabove-described function can be ensured. In the present embodiment,second valve seat part 173 is an annular protrusion.

Second diaphragm part 176 is a part of film 122. Second diaphragm part176 is disposed as a partition between the inside of channelopening-closing recess 172 and the inside of tube 110. In accordancewith the pressure of the irrigation liquid in tube 110, second diaphragmpart 176 deforms to make contact with second valve seat part 173. To bemore specific, as the pressure of the irrigation liquid increases,second diaphragm part 176 deforms toward second valve seat part 173, andwhen the pressure of irrigation liquid becomes the first pressure,second diaphragm part 176 makes contact with second valve seat part 173.In this manner, second channel 154 (second discharging through hole 175)is closed.

Second screen part 177 sends the irrigation liquid to the front surfaceof second diaphragm part 176 with almost no change in pressure of theirrigation liquid. Second screen part 177 includes a part of coverrecess 135, some of projected lines 136, and channel opening-closingthrough hole 178. Channel opening-closing through hole 178 is formed ina bottom portion of cover 123 at a position corresponding to seconddiaphragm part 176. The shape and number of channel opening-closingthrough hole 178 are not limited as long as the above-described functioncan be ensured. Channel opening-closing through hole 178 may have acircular shape or a rectangular shape in plan view. In the presentembodiment, channel opening-closing through hole 178 has a rectangularshape in plan view. In addition, the number of channel opening-closingthrough hole 178 is not limited. In the present embodiment, channelopening-closing through hole 178 is five long holes formed along theminor axis direction of the bottom surface of cover recess 135. The longholes are covered with projected lines 136, and therefore each channelopening-closing through hole 178 appears to be divided into multiplethrough holes as viewed from the front side.

Discharging part 181 is disposed on the rear surface side of emitter 120facing discharging port 111. Discharging part 181 sends the irrigationliquid from first discharging through hole 165 and second dischargingthrough hole 175 to discharging port 111 of tube 110. The configurationof discharging part 181 is not limited as long as the above-describedfunction can be ensured. In the present embodiment, discharging part 181includes discharging recess 182, a pair of discharging grooves 183, anda pair of entry preventing parts 184.

Discharging recess 182 opens at the rear surface of emitter main body121. Discharging recess 182 has a substantially rectangular shape inplan view. The pair of discharging grooves 183 open toward each other atopposite side surfaces of discharging recess 182.

The pair of entry preventing parts 184 prevents entry of foreign mattersfrom discharging port 111. The position of entry preventing part 184 isnot limited as long as the above-described function can be ensured. Inthe present embodiment, entry preventing part 184 is disposed such thatentry preventing part 184 is located between first discharging throughhole 165 and discharging port 111, and between second dischargingthrough hole 175 and discharging port when emitter 120 is joined to tube110.

Operations of Drip Irrigation Tube and Emitter

Next, an operation of drip irrigation tube 100 is described. First,irrigation liquid is fed into tube 110. Examples of the irrigationliquid include water, liquid fertilizer, agricultural chemicals andmixtures thereof. Preferably, the pressure of the irrigation liquid thatis fed to drip irrigation tube 100 is 0.1 MPa or lower in view of simplyimplementing the drip irrigation method, or preventing damaging of tube110 and emitter 120. The irrigation liquid in tube 110 is taken intoemitter main body 121 from liquid intake part 131. To be more specific,the irrigation liquid in tube 110 enters cover recess 135 from the gapbetween each projected line 136, and passes through first intake throughhole 133 and second intake through hole 134. At this time, liquid intakepart 131 can remove floating matters in the irrigation liquid sinceliquid intake part 131 includes liquid intake screen part 132 (the gapbetween each projected line 136).

The irrigation liquid taken from liquid intake part 131 reaches theupstream end of bypass channel 151. The irrigation liquid reachingbypass channel 151 flows toward the downstream of bypass channel 151,and flows into pressure reducing channel 141. At this time, theirrigation liquid first advances through bypass channel 151 that causessmaller pressure drop and has a shorter channel length in comparisonwith pressure reducing channel 141. The irrigation liquid having enteredbypass channel 151 flows into channel opening-closing part 171.

The irrigation liquid having entered channel opening-closing part 171flows into discharging part 181 when channel opening-closing part 171 isopen. The irrigation liquid having entered discharging part 181 isdischarged out of tube 110 from discharging port 111 of tube 110. On theother hand, the irrigation liquid having entered pressure reducingchannel 141 reaches flow rate reducing part 161. The irrigation liquidhaving entered flow rate reducing part 161 flows into discharging part181. The irrigation liquid having entered discharging part 181 isdischarged out of tube 110 from discharging port 111 of tube 110.

As described above, in flow rate reducing part 161, the flow rate of theirrigation liquid is controlled by first diaphragm part 166 inaccordance with the pressure of the irrigation liquid in tube 110,whereas in channel opening-closing part 171, the flow rate of theirrigation liquid is controlled by second diaphragm part 176 inaccordance with the pressure of the irrigation liquid in tube 110. Inview of this, operations of channel opening-closing part 171 and flowrate reducing part 161 according to the pressure of the irrigationliquid in tube 110 are described below.

FIGS. 8A to 8C are sectional views of emitter 120 illustrating arelationship between operations of flow rate reducing part 161 andchannel opening-closing part 171. FIG. 8A is a sectional view of a statewhere no irrigation liquid is fed to tube 110, FIG. 8B is a sectionalview of a state where the pressure of the irrigation liquid in tube 110is a first pressure, and FIG. 8C is a sectional view of a state wherethe pressure of the irrigation liquid in tube 110 is a second pressuregreater than the first pressure. FIG. 9 is a graph showing an exemplaryrelationship between the pressure of the irrigation liquid in tube 110and the flow rate of the irrigation liquid dropped from discharging port111. In FIG. 9, the solid line indicates a total flow rate of theirrigation liquid dropped from discharging port 111, the broken lineindicates a flow rate of the irrigation liquid having flown through(bypass channel 151) second channel 154, and the dashed line indicates aflow rate of the irrigation liquid having flown through (pressurereducing channel 141) first channel 153. In FIG. 9, the abscissaindicates a pressure (MPa) of irrigation liquid, and the ordinateindicates a flow rate (L/h) of the irrigation liquid discharged fromdischarging port 111.

Before irrigation liquid is fed to tube 110, the pressure of theirrigation liquid is not applied to film 122, and therefore firstdiaphragm part 166 and second diaphragm part 176 are not deformed (seeFIG. 8A).

When feeding of irrigation liquid into tube 110 is started, firstdiaphragm part 166 of flow rate reducing part 161 starts to deformtoward first valve seat part 163. In addition, second diaphragm part 176of channel opening-closing part 171 starts to deform toward second valveseat part 173. However, in this state, first diaphragm part 166 is notin contact with first valve seat part 163, and second diaphragm part 176is not in contact with second valve seat part 173, and therefore, theirrigation liquid taken from liquid intake part 131 is discharged to theoutside from discharging port 111 of tube 110 through first channel 153(pressure reducing channel 141, flow rate reducing part 161 anddischarging part 181) and second channel 154 (bypass channel 151,channel opening-closing part 171, flow rate reducing part 161 anddischarging part 181). In this manner, when the feeding of irrigationliquid into tube 110 is started, or when the pressure of the irrigationliquid in tube 110 is low, or the like, the irrigation liquid taken fromliquid intake part 131 is discharged through pressure reducing channel141 and bypass channel 151.

When the pressure of the irrigation liquid in tube 110 reaches the firstpressure, second diaphragm part 176 makes contact with second valve seatpart 173 and closes second channel 154 (see FIG. 8B). At this time,first diaphragm part 166 is not in contact with first valve seat part163. In this manner, when the pressure of the irrigation liquid in tube110 is so increased as to deform film 122, second diaphragm part 176comes closer to second valve seat part 173, and accordingly the amountof the irrigation liquid that is discharged through second channel 154decreases. Then, when the pressure of the irrigation liquid in tube 110reaches the first pressure, the irrigation liquid in second channel 154is not discharged from discharging port 111. As a result, the irrigationliquid taken from intake part 131 is discharged to the outside fromdischarging port 111 of tube 110 through first channel 153.

When the pressure of the irrigation liquid in tube 110 furtherincreases, first diaphragm part 166 further deforms toward first valveseat part 163. In a normal configuration, the amount of the irrigationliquid that flows through first channel 153 increases as the pressure ofthe irrigation liquid increases; however, in emitter 120 according tothe present embodiment, excessive increase in the amount of theirrigation liquid that flows through first channel 153 is prevented byreducing the pressure of the irrigation liquid with pressure reducingchannel 141 and by reducing the distance between first diaphragm part166 and first valve seat part 163. When the pressure of the irrigationliquid in tube 110 is equal to or greater than the second pressure,which is greater than the first pressure, first diaphragm part 166 makescontact with first valve seat part 163 (see FIG. 8C). Even in thisstate, neither of flow rate reducing through hole 168, communicationgroove 164 nor first discharging through hole 165 is closed by firstdiaphragm part 166, and accordingly the irrigation liquid taken fromliquid intake part 131 is discharged to the outside from dischargingport 111 of tube 110 through communication groove 164. In this manner,in flow rate reducing part 161, second diaphragm part 176 makes contactwith second valve seat part 173 when the pressure of the irrigationliquid in tube 110 is equal to or greater than the second pressure, andthus increase of the amount of the irrigation liquid flowing throughfirst channel 153 is suppressed (see the dashed line indicated in FIG.9).

As described above, flow rate reducing part 161 and channelopening-closing part 171 operate such that the amounts of the liquidflowing therethrough are offset each other in accordance with thepressure of the irrigation liquid in tube 110, and thus drip irrigationtube 100 according to the present embodiment can discharge a constantamount of irrigation liquid out of tube 110 regardless whether thepressure of the irrigation liquid is high or low (see the solid lineindicated in FIG. 9).

Effect

As described above, drip irrigation tube 100 according to the presentembodiment includes channel opening-closing part 171 that operatesmainly in the low pressure state, and flow rate reducing part 161 thatoperates mainly in the high pressure state. Thus drip irrigation tube100 according to the present embodiment can quantitatively drop theirrigation liquid regardless of the pressure of the irrigation liquid intube 110.

While pressure reducing groove 142 and bypass groove 152 open at thefirst surface, and serve as first channel 153 and second channel 154,respectively when the openings thereof are closed with film 122 in thepresent embodiment, pressure reducing groove 142 and bypass groove 152may open at the second surface. In this case, the openings of pressurereducing groove 142 and the opening of bypass groove 152 are closed bythe inner wall surface of tube 110. In addition, first channel 153 andsecond channel 154 may be formed inside emitter main body 121.

In addition, while the contact timing of deformed film 122 is adjustedby changing the positions (heights) of first valve seat part 163 andsecond valve seat part 173, the positions (heights) of first valve seatpart 163 and second valve seat part 173 may be set at the same depth. Inthis case, the contact timing of deformed film 122 may be adjusted bychanging the thicknesses and/or the materials (elasticities) of firstdiaphragm part 166 and second diaphragm part 176.

In addition, while flow rate reducing part 161 and channelopening-closing part 171 are independent of each other in the presentembodiment, flow rate reducing part 161 and channel opening-closing part171 may be communicated with each other.

This application is entitled to and claims the benefit of JapanesePatent Application No. 2016-054104 filed on Mar. 17, 2016, thedisclosure each of which including the specification, drawings andabstract is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

According to the present invention, an emitter which can drop liquidwith an appropriate rate by the pressure of the liquid to be dropped canbe easily provided. Accordingly, popularization of the emitter in thetechnical fields of drip irrigations and endurance tests where long-termdropping is required, and development in the technical fields can beexpected.

REFERENCE SIGNS LIST

-   100 Drip irrigation tube-   110 Tube-   111 Discharging port-   120 Emitter-   121 Emitter main body-   122 Film-   123 Cover-   131 Liquid intake part-   132 Liquid intake screen part-   133 First intake through hole-   134 Second intake through hole-   135 Cover recess-   136 Projected line-   141 Pressure reducing channel-   142 Pressure reducing groove-   143 Protrusion-   151 Bypass channel-   152 Bypass groove-   153 First channel-   154 Second channel-   161 Flow rate reducing part-   162 Flow rate reducing recess-   163 First valve seat part-   164 Communication groove-   165 First discharging through hole-   166 First diaphragm part-   167 First screen part-   168 Flow rate reducing through hole-   171 Channel opening-closing part-   172 Channel opening-closing recess-   173 Second valve seat part-   175 Second discharging through hole-   176 Second diaphragm part-   177 Second screen part-   178 Channel opening-closing through hole-   181 Discharging part-   182 Discharging recess-   183 Discharging groove-   184 Entry preventing part

1. An emitter including an emitter main body, a film having flexibilitydisposed on a first surface of the emitter main body, and a cover forpositioning the film with respect to the emitter main body, the emitterbeing configured to be joined on an inner wall surface of a tubeconfigured to distribute irrigation liquid at a position correspondingto a discharging port communicating between inside and outside of thetube, the emitter being configured to quantitatively discharge theirrigation liquid in the tube to the outside of the tube from thedischarging port, the emitter comprising: a liquid intake part forreceiving the irrigation liquid; a discharging part disposed in a secondsurface of the emitter main body and configured to discharge theirrigation liquid, the second surface being opposite to the firstsurface and being configured to face the discharging port; a firstchannel configured to connect the liquid intake part and the dischargingpart together, and to distribute the irrigation liquid; a second channelconfigured to connect the liquid intake part and the discharging parttogether, and to distribute the irrigation liquid; a flow rate reducingpart disposed in the first channel and including a flow rate reducingrecess opening at the first surface and the film closing an opening ofthe flow rate reducing recess, the flow rate reducing part beingconfigured to reduce a flow rate of the irrigation liquid flowing to thedischarging port by deformation of the film in accordance with apressure of the irrigation liquid in the tube; a channel opening-closingpart disposed in the second channel and including a channelopening-closing recess opening at the first surface and the film closingan opening of the channel opening-closing recess, the channelopening-closing part being configured to open and close the secondchannel by deformation of the film in accordance with a pressure of theirrigation liquid in the tube; a pressure reducing channel disposed inthe first channel located upstream of the flow rate reducing part, thepressure reducing channel being configured to guide, to the flow ratereducing part, the irrigation liquid received from the liquid intakepart while reducing a pressure of the irrigation liquid received fromthe liquid intake part; and a bypass channel disposed in the secondchannel located upstream of the channel opening-closing part, the bypasschannel being configured to guide, to the channel opening-closing part,the irrigation liquid received from the liquid intake part whilemaintaining a pressure of the irrigation liquid received from the liquidintake part at a pressure higher than a pressure of the irrigationliquid which has flown through the pressure reducing channel, whereinwhen the pressure of the irrigation liquid flowing through the tube islower than a first pressure, the irrigation liquid received from theliquid intake part is guided to the discharging part through thepressure reducing channel and the bypass channel, and wherein when thepressure of the irrigation liquid flowing through the tube is equal toor higher than the first pressure, the second channel is closed by thechannel opening-closing part, and the irrigation liquid received fromthe liquid intake part is guided to the discharging part through thepressure reducing channel.
 2. The emitter according to claim 1, whereinthe flow rate reducing part and the channel opening-closing part areindependent of each other; wherein the irrigation liquid from thepressure reducing channel is guided to the discharging part through theflow rate reducing part; and wherein the irrigation liquid from thebypass channel is guided to the discharging part through the channelopening-closing part.
 3. The emitter according to claim 1, wherein theflow rate reducing part includes: the flow rate reducing recess, whereinthe pressure reducing channel opens at an inner surface of the flow ratereducing recess; a first diaphragm part of the film, the first diaphragmpart being disposed such that the first diaphragm part serves as apartition between inside of the flow rate reducing recess and inside ofthe tube; a flow rate reducing through hole opening at the inner surfaceof the flow rate reducing recess, and communicated with the dischargingpart; a first valve seat part disposed to surround the flow ratereducing through hole such that the first valve seat part faces thefirst diaphragm part with a space between the first valve seat part andthe first diaphragm part, the first valve seat part being configured toallow the first diaphragm part to make intimate contact with the firstvalve seat part when the pressure of the irrigation liquid flowingthrough the tube is equal to or higher than a second pressure, thesecond pressure being higher than the first pressure; and acommunication groove formed in a first surface of the first valve seatpart, the first surface being a surface on which the first diaphragmpart is allowed to make intimate contact with the first valve seat part,the communication groove being configured to communicate between theinside of the flow rate reducing recess and the flow rate reducingthrough hole.
 4. The emitter according to claim 1, wherein the channelopening-closing part includes: the channel opening-closing recess,wherein the bypass channel opens at an inner surface of the channelopening-closing recess; a second diaphragm part of the film, the seconddiaphragm part being disposed such that the second diaphragm part servesas a partition between inside of the channel opening-closing recess andinside of the tube; a channel opening-closing through hole opening atthe inner surface of the channel opening-closing recess and communicatedwith the discharging part; and a second valve seat part disposed tosurround the channel opening-closing through hole such that the secondvalve seat part faces the second diaphragm part with a space between thesecond valve seat part and the second diaphragm part, the second valveseat part being configured to allow the second diaphragm part to makeintimate contact with the second valve seat part when the pressure ofthe irrigation liquid flowing through the tube is equal to or higherthan the first pressure.
 5. The emitter according to claim 1, whereinthe discharging part includes an entry preventing part for preventingentry of foreign matters from the discharging port.
 6. A drip irrigationtube, comprising: a tube including a discharging port for dischargingirrigation liquid; and the emitter according to claim 1, the emitterbeing joined on the inner wall surface of the tube at a positioncorresponding to the discharging port.